Apical root resorption due to mandibular first molar mesialization: A split-mouth study.

INTRODUCTION: Our aim was to evaluate the risk of external apical root resorption (EARR) in mesialized mandibular molars due to space closure in patients with unilateral second premolar agenesis. The contralateral side served as the control. METHODS: After application of eligibility criteria, 25 retrospectively selected subjects (median age, 14.9 years; range, 12.0-31.9 years) were analyzed. Space closure (approximately 10 mm) was performed using skeletal anchorage. EARR was measured at the mandibular permanent canines, first premolars, and first molars in the pretreatment and posttreatment orthopantomograms. Measurements were performed by 2 examiners independently and were corrected for distortion and magnification of radiographs, which were assessed in a pilot study. Multivariate analysis of covariance and pairwise comparisons were performed. RESULTS: The mean enlargement factor of the panoramic machine was 29% ± 0.3%. Distortion exceeded 5% only in cases of large positioning errors (>20°). Intraclass correlation coefficients showed strong to almost perfect agreement (mean, 0.80 mm; 95% CI, 0.75-0.85) of the two examiners. Multivariate analysis of covariance resulted in no difference in EARR between the canines and premolars of the space closure and control sides. On the contrary, there was a statistically significant difference between mesialized and nonmezialized molars (0.73 mm; 95% confidence interval, 0.19-1.27). The mean total EARR in each tooth type did not exceed 1 mm. CONCLUSIONS: Space closure through extensive tooth movement in the mandible was identified as a risk factor for EARR. However, the amount of EARR attributed to space closure and the total EARR were not considered clinically significant.

Effect of different incisor movements on the soft tissue profile measured in reference to a rough-surfaced palatal implant.

INTRODUCTION: The aim of this study was to evaluate soft tissue profile changes after a wide range of incisor movements in the anterior and posterior directions in nongrowing patients. Identifying baseline values more prone to substantial soft tissue profile changes was of high interest. METHODS: For this retrospective study, 47 pairs of lateral cephalograms of nongrowing white patients were superimposed. The cephalograms were taken with the same palatal implant in situ before and after treatment. To increase the accuracy of the measurements, the palatal implants were used as stable reference structures in close relation to the incisors. RESULTS: Horizontal changes of the most anterior point of the maxillary incisor showed a significant correlation to horizontal changes of the upper and lower lips (P <0.001). For every millimeter of horizontal change of the most anterior point of the maxillary central incisor, a change of 0.59 mm at labrale superior can be expected. Also, the angulations of the upper and lower lips were significantly correlated to the most anterior point of the maxillary incisor. Lip retraction was less pronounced in patients with initially thicker lips than in those with thinner lips. CONCLUSIONS: The major contributing factors for predicting the soft tissue profile change during orthodontic treatment are the amount of horizontal movement of the most anterior point of the maxillary incisor, the amount of bite opening, and the initial lip thickness. Although there are significant correlations between dental movements and soft tissue changes in larger samples, predictions for individuals may be inconsistent.

Noninvasive palatal implant removal.

OBJECTIVE: Orthodontic palatal implants are commonly used and do provide reliable absolute anchorage to assist orthodontic treatment. However, once treatment is completed, removal of these temporary implants is not considered easy or risk free. This short communication presents a clinical case in which a novel noninvasive procedure was applied to remove an osseointegrated palatal implant. MATERIAL AND METHODS: A customized explantation tool, tightly fixed to the implant and precisely grasping the implant's head, was used in combination with a ratchet to unscrew the implant instead of the traditional removal by trephine. RESULTS: Only a topical anesthetic was necessary before the implant-bone contact was broken by turning the ratchet counterclockwise. The implant was retrieved without any local anesthesia. The explanted palatal implant had no bone appending to it, except in its apical anti-rotational grooves, and the healing process thereafter was unproblematic. CONCLUSIONS: Noninvasive palatal implant removal offers a simple and fast approach for explantation. Moreover, it might reduce the risk of adverse patient reactions, iatrogenic tooth and nerve injuries, and possible oro-antral communications.

Non-invasive removal of sandblasted and acid-etched titanium palatal implants, a retrospective study.

BACKGROUND: Short, rough-surfaced palatal implants are an established and reliable anchor for orthodontic treatment. Until recently, removal was only possible surgically using a hollow cylinder trephine. This standard method retrieves the implant combined with a larger bone volume and is therefore considered invasive and has known complications. Lately, an explantation tool which allows a sufficient force application to break the bone-implant-connection and unscrew the palatal implant was developed and, since its introduction, has been used as the method of choice in several orthodontic offices. OBJECTIVES: The aim of this study was to assess the complications caused by removing rough-surfaced palatal implants simply by unscrewing them with an explantation tool in contrast to standard protocol by surgical removal with a trephine. MATERIAL AND METHODS: The removal of 73 palatal implants using a customized explantation tool has been evaluated retrospectively and was compared to an existing sample of 44 conventional surgical explantations. RESULTS: The new clinical procedure resulted in successful removal of 71 (97.3 per cent) palatal implants. In two cases, the new method failed but removal with the established surgical method was still possible with no further complications. The non-invasive palatal implant removal with a customized explantation tool had less medical complications compared to an existing sample of surgical explantations. CONCLUSIONS: User's opinion was that the new method is more easily executed, less invasive, and also applicable without local anaesthesia. Therefore, it is considered to be beneficial for patients and the treatment approach of choice. However, further research is needed for verification.

Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients.

OBJECTIVE: To evaluate the demographic, radiological and therapeutic parameters that influence the overall clinical performance of palatal implants subjected to orthodontic loading. PATIENTS AND METHODS: The data of all patients who had received an orthodontic palatal implant for skeletal anchorage between January 1998 and December 2007 were reviewed retrospectively. The primary endpoint was the implant loss. The following parameters were assessed by univariate (log-rank test) and multivariate (Cox's regression) analysis: (a) age and gender, (b) vertical bone height along the prospective implant axis, (c) surgeon's experience and (d) implant type. RESULTS: Two-hundred and thirty-nine palatal implants were inserted in patients aged between 10 and 65 years. In all, 11/239 (4.6%) implants were lost: nine during the healing phase and two under functional loading. On univariate analysis, "surgeon's experience" was associated with a better implant survival and vice versa (P=0.0005; log-rank test). The significance of "surgeon's experience" was confirmed by Cox's regression analysis (P=0.001; Wald test). All other parameters had no impact on implant loss. CONCLUSIONS: The survival probability of palatal implants is not related to demographic and radiological parameters. Implant losses mainly occurred early in the healing phase of the palatal implant. According to our data, "surgeon's experience" is the cornerstone of palatal implant success.

Immediate vs. conventional loading of palatal implants in humans.

OBJECTIVES: To analyze the clinical performance and bone-to-implant contact (BIC) rate of two loading concepts on successfully healed and explanted palatal implants in humans. METHODS: From 2000 to 2006, two independent groups of patients, requiring maximum anchorage, were treated. Group 1 (n=36) was subjected to immediate functional loading within the first 24 h after insertion while group 2 (n=40) received conventional implant loading after 12 weeks. The magnitude of orthodontic forces ranged between 1 and 3 N. After orthodontic treatment, the implants were removed with a trephine drill. Histological workup by the cutting and grinding technique was performed for nearly the last third of palatal implants. Outcome variables were clinical implant survival and histological BIC rates. RESULTS: The implants in both groups were initially stable at the time of insertion. However, 3/36 in group 1 and 1/40 in group 2 were lost. The remaining implants were clinically stable and no mobility was recognized. The median BIC rates were 76% (SD, 25) in group 1 (n=10) and 84% (SD, 13) in group 2 (n=12) (P=0.262; Mann-Whitney U-test, not significant). CONCLUSIONS: The data support the concept of immediate indirect loading on palatal implants with forces of up to 3 N. On histological evaluation, immediate loading yielded similar BIC rates as conventional loading.

New method of temporary rehabilitation after traumatic tooth loss in a juvenile patient: a case report.

We report a 12-year-old female patient who had experienced traumatic loss of one of her permanent central incisors. In the course of interdisciplinary treatment, the gap in the front teeth was filled with a prosthetic plastic tooth fastened to an orthodontic palatal implant by means of a wire extension (stainless steel 1.2 mm; laser-welded). A palatal implant is a temporary orthodontic anchorage device which, in contrast to a conventional single tooth implant, is not inserted in the toothless alveolar bone but in the palatal region to permit unhindered maxillary growth. The advantages of this treatment compared with traditional treatment options are that it permits secure fixation, adjustment to vertical growth and good hygiene. Besides, it is an economical treatment modality, can be used as anchorage in conjunction with orthodontic treatment and provides good comfort, esthetics and phonetics.

Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study.

INTRODUCTION: The aim of this study was to determine the positional stability and success rate of palatally placed length-reduced temporary anchorage devices (LRTADs) (length, 4 or 6 mm). METHODS: Twenty-two patients (ages, 21-62 years; 14 women, 8 men) were enrolled in the study. Each received 1 LRTAD (Orthosystem, Straumann, Switzerland) placed in the midsagittal palate for multifunctional anchorage tasks. Standardized cephalograms were taken directly after implant placement and at the end of treatment to analyze any implant movements. The cephalometric tracings were superimposed on anterior nasal spine to posterior nasal spine in posterior nasal spine to analyze changes in implant angulation and position during treatment. The LRTADs were also evaluated clinically for mobility. RESULTS: Two of 22 implants showed mobility during the healing period (first 10-12 weeks after placement). Thus, the success rate was 91%. The remaining 20 palatally placed LRTADs had no mobility during healing (10-12 weeks) or the loading period (18 months 1 week) and were evaluated radiographically. The mean differences between the initial and final cephalometric evaluations (n = 20) were 0.5 degrees for changes in implant angulation and -0.6 mm for changes in implant position. These changes were most likely due to inaccuracies in cephalometric landmark identification rather than to LRTAD movements because no mobility was recorded. CONCLUSIONS: One palatally placed LRTAD was sufficient for multifunctional stationary anchorage tasks in the maxilla under clinical loading conditions. The success rate was 91%. Implant loss occurred during the healing period.

Success rate of second-generation palatal implants.

OBJECTIVE: To analyze the clinical outcome of a prospective two-center study of second-generation palatal implants 6 months after functional loading. MATERIAL AND METHODS: From 2005 to 2006, 30 patients aged 12 to 41 years were included in the study. In all patients, orthodontic treatment required stationary anchorage. The palatal implants (Straumann, Basel, Switzerland) were placed in the median region of the anterior palate. RESULTS: All implants were initially stable at the time of placement. However, two (6.7%) were lost during the unloaded healing period. The remaining 28 (93.3%) were subjected to functional loading after a mean healing period of 12 weeks. Typical signs of slight superficial inflammation were observed in the peri-implant mucosa (n = 28). During the orthodontic loading phase, the implants were equipped with either a modified pendulum appliance for distalization or a transpalatal arch for stationary anchorage to the posterior teeth. No implant loosening or loss was registered during the active treatment period. CONCLUSIONS: The failure rate of palatal implants of the second generation was low (6.7%). Slight inflammatory reactions of peri-implant tissue caused neither implant loss nor pain.

Effect of mandibular first molar mesialization on alveolar bone height: a split mouth study.

OBJECTIVES: To evaluate the risk of vertical alveolar bone loss (ABL) in mesialized mandibular permanent molars due to space closure in patients with unilateral second premolar agenesis. The contralateral side served as control. SUBJECTS AND METHODS: Twenty-five retrospectively selected subjects (median age 14.9, range 12.0, 31.9 years) were analyzed. Space closure (approximately 10 mm) was performed using skeletal anchorage. ABL was measured at mesial and distal sites of first molars in pre- and post-treatment panoramic radiographs. Measurements were corrected for distortion and magnification of radiographs. Molar angulation according to the occlusal plane was also evaluated. Permutational multivariate analysis of covariance (MANCOVA), followed by pairwise comparisons, was performed. RESULTS: MANCOVA resulted in no difference in ABL between the distal sites of mesialized molars and the control sites. On the contrary, there was statistically higher ABL, at the mesial sites of mesialized versus non-mesialized molars (p = 0.042; median 0.19 mm; range - 0.82, 1.33); though the difference was not clinically relevant. In the space closure side, mesially, only two patients had ABL higher that 1 mm. No patient had a severe bone level height defect (> 3 mm distance from the cementoenamel junction) at any point. When testing differences in molar angulation between sites and from pre- to post-treatment condition, no significant difference was detected (p > 0.05, median - 1.9°, range - 13.5, 6.2). LIMITATIONS: This is a retrospective study on panoramic radiographs. CONCLUSIONS: Space closure through extensive tooth movement was identified as a risk factor for vertical ABL, at the mesial sites of mandibular first molars. However, the amount of ABL was not clinically relevant, and thus this treatment option is considered safe in terms of ABL.

Miniscrews or palatal implants for skeletal anchorage in the maxilla: comparative aspects for decision making.

The advantages and disadvantages associated with placement, orthodontic treatment, and removal of miniscrews and palatal implants should be clearly understood by both the orthodontist and the patient. Device design, preoperative diagnostic measures, insertion and removal procedures, potential suprastructure application, implant migration and success rate, biomechanical anchorage facilities, and comparative risks and complications of both miniscrews and palatal implants must be considered if skeletal anchorage is intended to be used in the maxilla. This article reviews these and other factors to help clinicians decide which device should be selected for each individual case.

Skeletal anchorage in orthodontics--basics and clinical application.

This review article describes the basics and clinical applications of skeletal anchorage in orthodontics, namely: areas of indication, anchorage devices, insertion areas, indications, potential complications, and their use in growing patients. The areas for skeletal anchorage include orthodontic-prosthetic anchorage, orthodontic anchorage, and skeletal anchorage in orthopedic therapy procedures. The anchorage devices currently available are: prosthetic implants, mini screws, palatal implants, onplants, bone anchors, zygoma wires and skeletally-supported distractors. The insertion areas described so far (according to therapeutic procedure and bone supply available) include edentulous jaw sections, the interdental septum, infra-apical and supra-apical areas, the palate (median, paramedian, lateral), the retromolar area, and the zygomatic bone. Force systems are applied (direct or indirect anchorage) according to surgical and orthodontic or orthopedic requirements. Skeletal anchorage devices should be selected according to the following criteria. Is the anchorage task unifunctional or multifunctional? How many anchorage devices are required for the therapy in question? What is the success rate of the various anchorage devices; what are the applicable biomechanics and soft tissue or hard tissue conditions in the insertion area? The success rates for miniscrews are currently between 80% and 90%, and over 90% for palatal implants. The potential of skeletal anchorage is broadening the current orthodontic treatment spectrum, guaranteeing the practitioner absolute control of anchorage by avoiding the unpredictable reactions of periodontal anchorage, leading to a reduction in unwanted side effects.

Does thread design influence relative bone-to-implant contact rate of palatal implants?

AIM: To determine histologically whether (a) changing the thread design between first- and second-generation palatal implants (Straumann, Basel, Switzerland) influences the bone-to-implant contact (BIC) rate of palatal implants subjected to conventional loading, and (b) whether histological evidence of peri-implantitis appears in this setting. PATIENTS AND METHODS: Patients who had received an orthodontic palatal implant for skeletal anchorage between January 1998 and December 2007 were examined. First-generation palatal implants (Straumann, Basel, Switzerland) 3.3 mm in diameter and 6 mm or 4 mm long were used, as were second-generation implants 4.1 mm in diameter and 4.2 mm long. After completion of active orthodontic treatment, the implants were removed and prepared for histological investigation. This study was designed as a comparative analysis of a series of two cases: 28 explanted first-generation (n = 14) and second-generation (n = 14) palatal implants were analyzed. RESULTS: Bone healing was achieved with all implants. Both types of implants revealed a mean bone-to-implant contact (BIC) rate that was nearly equal: 80.7% (SD 10.7%) for the first-generation and 81% (SD 13.1%) for the second-generation implants. Bone resorption was only observed in 5 palatal implants (3/14 of the first, and 2/14 of the second generation). CONCLUSION: Despite differing thread designs, second-generation palatal implants revealed similar bone-to-implant contact rates as did those of the first generation. Few patients presented bone resorption in the peri-implant bone.